Documentation

parseFromFile p filePath runs a parser p on the
input read from filePath using ByteString.readFile. All diagnostic messages
emitted over the course of the parse attempt are shown to the user on the console.

main = do
result <- parseFromFile numbers "digits.txt"
case result of
Nothing -> return ()
Just a -> print $ sum a

parseFromFileEx p filePath runs a parser p on the
input read from filePath using ByteString.readFile. Returns all diagnostic messages
emitted over the course of the parse and the answer if the parse was successful.